pass variable to custom operator through iteration
The problem is that in the execute function, s is not defined, you need to tell the operator what is s. 

A solution you could use is to add a property to the operator:

class AnimOperator(bpy.types.Operator):
    bl_idname = "object.anim_operator"
    bl_label = "Pose Anim Operator"
    s = bpy.props.StringProperty()
    ...
    def execute(self, context):
        revealfileexplorer(self.s)
        return {'FINISHED'}


notice the self.s to access the s in the AnimOperator class instance

Then when calling the operator, you have to define the value of s. 

op=layout.operator('reveal.file_explorer')
op.s = s


I didn't try this code so I maybe made some mistakes but you have the idea.

Those are object oriented programming and concepts and the scope of a variable problems, you'll maybe need to learn a little about that if you want to use programming language for more complex program.

Edit: I'm a little tired right now but looking back to you code there is another problem, you don't use s but rstrip in the revealfileexplorer function. I also suggest you to use the StringProperty but this will only accept text. I never tried to use complex types as operator parameter I think you are limited to Blender properties types but I'm not sure about that, I will test that tomorrow to give you a more precise answer if you need, but for now I think that you can solve your problem using only string, maybe with multiple StringProperty  if needed. You can also use a IntProperty, and pass the index as parameter, and then find your strip like that:

def revealfileexplorer (id):
     s = bpy.context.scene.sequence_editor.sequences_all[id]